I've got a similar situation with trimming along my split rail fence where I've got the wire fencing up against it and touching the ground. I'm now wishing I would have not made the wire touch the ground, but was trying to make it work well for keeping doggies inside.

I'm thinking of trying thicker trimmer line, as I'm using .080", and it goes through that like crazy, plus the trim isn't that clean. Though, I'm wondering if the thicker line will chew up the wire.

Hoping someone has experience with the scythe attachment too!

RoundUp.

Roundup would work but I'm not sure if it's good for the cattle or the hay.

I have one it works on short things like lawn grass but tall things like hay weeds it don't cut its way into if try to cut up next to mowed area they work the base hard to push to side in tall grass. Roundup want damage cattle to save money you use roundup as growth retartent .05 percent like pint in 25 gallons water if spray between 10 am and 4 pm it work best. On string trimmer use `105 line use extreme titaium line its purple and quad shape not round I bought 600 ft roll at lowes in 2002 this string stay with you not brake I use it on srm 210 echo. I can use it all around my home and never bump more out its great for edging and small hedge trimming. A 3 tooth grass blade works good for this job works better than 4 tooth.